This invention relates to a co-axial tube structure of the kind used in a flowing gas laser.
This invention relates particularly to a co-axial laser tube structure and related mounting structure which permit installation and/or replacement of the tubes without the need for subsequent adjustment or bore registration of the tubes.
In specific embodiments of the present invention the flowing gas is carbon dioxide gas, and the gas flows axially through a co-axial tube structure in the same general way as
described in copending U.S. patent application Ser. No. 811,593, filed Dec. 19, 1985 by Joseph F. Rando, et al. and entitled "Fast Axial Flow Laser Circulating System" and assigned to the same assignee as the assignee of this present application.
The gas flow path through the co-axial laser tube structure of the present invention is also generally like that shown in pending U.S. patent application Ser. No. 863,632, filed Nov. 14, 1986 by Robert B. Slusher, et al. and entitled "Fast Axial Flow Carbon Dioxide Laser" and assigned to the same assignee as the assignee of this present application.
The optics used in conjunction with the co-axial tube laser structure of the present invention, and the apparatus and techniques for maintaining the registry of the mounting blocks with respect to one another are substantially the same as that disclosed in pending U.S. patent application Ser. No. 034,342, filed Apr. 3, 1987 by Dale E. Koop and entitled "Cube Corner Polarizer" and assigned to the same assignee as the assignee of this present application.
Each of these three pending U.S. patent application Ser. Nos. 811,593 and 863,632 and 034,342 is incorporated by reference in the present application.
In flowing gas lasers of this kind two or more sets of co-axial laser tube structures may be used in tandem (and/or in parallel by means of a cube corner construction) to make up the complete light path between the reflecting mirrors.
The installation and the replacement of these co-axial tube structures require that the tube structure be installed in registry with the bore axis of the laser mode. Maintaining proper registry can present problems during either initial installation or subsequent replacement.
The co-axial construction of the tube structures can result in rather expensive tube constructions if blown glass techniques are used to make one piece, integral tube structures.
One piece, integral co-axial tube structures can also present special problems in installation and replacement.
A relatively high level of electrical power is required to produce the electrical discharge between the anode and cathode in high power carbon dioxide flowing gas lasers, and such high levels of electrical power can present problems of arcing at both the anode and the cathode.
Maintaining good gas flow dynamics can also be a problem with flowing gas lasers. Any losses because of undesired turbulence outside the discharge area, unrecovered pressure head drops or excessive thicknesses of boundary layer conditions can reduce the overall efficiency of the laser.
The hot end of the inner tube is subjected to substantial heat. This heat, particularly in combination with any impingement of parasitic modes on the end surface of the hot end of this tube, can result in chipping of the tube. Chipping of the end of the tube can require replacement of the tube.